Sole for boot, in particular a sports boot, a method of manufacturing same, and a boot having such a sole

ABSTRACT

A sole for a sports boot, such as for cross-country skiing, and, more particularly, a sole for a sports boot which makes it possible to improve the torsional stiffness, flexional flexibility, efficiency of the boot, durability, lesser weight, protection of the foot, cost savings, industrial workability. To this end, the sole has a front portion, a rear portion more rigid in longitudinal bending than the front portion, and a reinforcement. The front portion has a front half-sole affixed to the reinforcement, the rear portion has a rear half-sole affixed to the reinforcement, and the front and rear half-soles are assembled to one another in a junction zone, preferably by cementing and/or riveting and/or welding. In practice, the reinforcement is made of a composite material. The front half-sole is first fixed on the front portion of the reinforcement. The rear half-sole is then fixed by cementing on the rear portion of the reinforcement, such that its front portion overlaps the rear of the front half-sole. The invention also relates to methods of manufacturing the sole and the boot having such a sole. The boot itself is also covered by the invention.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is based upon French Patent Application No. 0015431, filed Nov. 29, 2000, the disclosure of which is herebyincorporated by reference thereto in its entirety, and the priority ofwhich is hereby claimed under 35 U.S.C. §119.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to the field of boots, inparticular sports boots, and more particularly boots adapted to sportsthat require rolling/unrolling movements of the foot and/or to glidingsports involving supports of the same name, such as, but not limited to,cross-country skiing.

[0004] The invention also relates to gliding sports not involvingrolling/unrolling movement of the foot, such as ice skating, rollerskating, with or without in-line wheels, snowboarding, skateboarding,etc.

[0005] The present invention relates to a sole, especially an outer solefor a boot, for example a sports boot. This sole is of the type of thosehaving a reinforcement or an insert made of a composite material adaptedto provide rigidity in the transverse direction (high torsionalstiffness), combined with a longitudinal flexibility, especially in themetatarsophalangeal zone (low longitudinal stiffness).

[0006] The invention also relates to methods of manufacturing theaforementioned soles via molding techniques.

[0007] Finally, the invention relates to a boot, especially a sportsboot, provided with such a sole.

[0008] 2. Description of Background and Relevant Information

[0009] Sports in which the foot and, therefore, the boot are subject tomore or less pronounced rolling/unrolling movements are, for example,hiking, running, biking, cross-country skiing involving the evolutivetechnique so-called “alternate step” or “skating step”, alpine skiing,telemark skiing, or snowshoeing, etc.

[0010] There are also gliding sports that do not involverolling/unrolling movement of the foot, such as ice skating, rollerskating, with or without in-line wheels, snowboarding, skateboarding,etc.

[0011] The aforementioned sports have common requirements with respectto the boot, and especially to the sole, which requirements are, at theoutset, incompatible.

[0012] In fact, all of the aforementioned sports generally require ashifting of the user's center of gravity from the heel zone of the footto the so-called metatarsophalangeal area of natural bending of thefoot, and vice versa. These shiftings serve to direct and/or propel theuser's body, for example, by means of edge setting or equivalentmaneuvers, such as the movement impulse performed by striding with aroller skate, or a cross-country ski, whether with the conventionaltechnique or the skating technique. These shiftings of the center ofgravity are accompanied by a transmission of forces in the heel zone, onthe one hand and, in some cases, by a bending in the metatarsophalangealbending zone, on the other hand.

[0013] This generates the requirement for a good transmission of theforces, without any losses by shock absorption and undesirabledeformation in the area between at least the heel and themetatarsophalangeal zone and, consequently, a requirement for rigidityof the sole in this zone, often accompanied by a requirement for asnatural a rolling/unrolling movement as possible and, therefore, forflexibility of the sole in the metatarsophalangeal zone, so that it canbend easily with respect to the metatarsophalangeal joint. This jointcan be defined as being that whose axis forms an angle of about 71° withthe internal tangent of the foot, and crosses the longitudinal medianaxis at about 73% of the total length of the foot, from the heel.

[0014] It is obvious that the integration of two different, and evenincompatible requirements in one element, i.e., the sole, generally canonly be performed to the detriment of one of these requirements, i.e.,the transmission of the forces coming from the leg in the zone comprisedbetween the heel and the metatarsophalangeal zone and/or the flexibilityin the latter zone.

[0015] The resulting problem is that, generally, this construction ofthe sole cannot meet all of the requirements at the same time, and itusually represents a more or less satisfactory compromise betweenrigidity and flexibility.

[0016] Another problem concerns the manufacture of the soles of theaforementioned type in one piece. These soles entail high manufacturingcosts, because it is necessary to provide soles of specific and variouslengths for all the desired sizes. This results in a necessity ofmanufacturing and storing a large number of different soles, and ofcutting the edges of a sole to obtain a smaller size. This lattertechnique, which is only used for the wear soles, is a waste of materialand burdens the production costs.

[0017] In addition to the mechanical characteristics of torsionalstiffness in the rear portion and of flexibility in longitudinal bendingalong the metatarsophalangeal axis, other parameters must be taken intoconsideration, including, in particular, lightness, cost, industrialworkability, and durability.

[0018] It is known to use upper/vamp or sole reinforcements in anattempt to control rigidity and bending. A certain number of priortechnical propositions exist, but none is entirely satisfactory.

[0019] The patent document No. EP 0 931 470 describes a sports bootincluding a stiffening element integrated into the lower portion (soleunit of the boot). This stiffening element is an insole or an outsole ora sandwich-type internal reinforcement including an inner layer 15 madeof expanded plastic foam (made of light wood, touching plasticcylinders, cellular or honeycombed core), this core being insertedbetween two layers 13 and 14 based on polymer (nylon, polyurethane,polypropylene), resin or composite material including synthetic resinsin which carbon, aramide or glass fibers are inserted. The rigidity ofthe layers 13 and 14 is greater than that of the inner layer 15. Thethickness of the latter is greater than that of the layers 13 and 14. Itis apparent from FIG. 5 and the text, column 3, lines 41-53, of EP 0 931470 that the stiffening element can include portions of variablecross-section and different flexibilities, in particular having greaterlongitudinal flexibility at the forefoot.

[0020] The sandwich reinforcement according to EP 0 931 470 is adaptedto provide rigidity to the sole unit so as to render it rigid, or atleast semi-rigid. The target applications are mountain boots, cyclingshoes, and roller skate boots. In all these applications, it is clearthat one is not looking for a longitudinal flexibility in themetatarsophalangeal area which would enable rolling/unrolling movementswith respect to the front tip of the foot. In addition, this stiffeningelement complicates the manufacture and appears to be perfectible withrespect to its mechanical properties.

[0021] The French Patent Publication No. 2 600 868 (based uponApplication No. 86 10130) relates to a sole for a cross-country skiboot, which is stiff in torsion and flexible in the longitudinaldirection. This sole includes a reinforcement located at least in themetatarsophalangeal zone and corresponding to an insole constituted by acomposite sheet (glass, carbon or aramide fibers embedded in epoxy orpolyester resins). This composite sheet has the characteristic of havingfibers that are oriented in two or three directions with respect to thelongitudinal axis of the sole (multidirectional fabric). This issupposed to enable desired stiffnesses to be obtained in thelongitudinal transverse direction or in torsion. Furthermore, this bootsole does not have optimum qualities with respect to transverserigidity, therefore with respect to the steering of the ski,flexibility, durability, lightness, efficiency, uniformity andsensitivity of the rolling/unrolling movement, and with respect to theprotection of the foot during bendings.

[0022] The French Patent Publication No. 2 682 011 (based uponApplication No. 91 12376) relates to a cross-country ski boot whosetorsional stiffness and longitudinal flexibility in themetatarsophalangeal zone are improved, and which has an outer solecovered by an insole defining therebetween a peripheral assembly zone,so-called lasting allowance, which makes it possible to affix the upperand the vamp to the lower portion of the boot. The outer sole hasproperties of torsional rigidity, and it is mounted in combination withthe insole made of a flexionally flexible material (rubber) in a zonecorresponding to the front portion of the foot. Furthermore, the insoleis made of leather or cellulose fibers in its front end areacorresponding to the zone of the toe bones, while the rear portion ismade, for example, of cardboard.

[0023] In this boot, the torsional stiffness in the zone of themetatarsophalangeal bending axis and, therefore, the control of the skiremain perfectible.

[0024] Furthermore, this boot could also be improved with respect tooptimizing its efficiency, which results from the spring effect in thiszone of the metatarsophalangeal bending axis.

[0025] Finally, the materials used in the insole of this boot do notoffer all the desired guarantees in terms of stability of the mechanicalproperties over time.

[0026] The prior art also includes a certain number of references thatare directed more specifically to soles, and which will be addressedhereinafter.

[0027] U.S. Pat. No. 2,581,524 proposes to manufacture a two-partmidsole. However, this sole is adapted to a boot for spare-timeactivities and, consequently, the rear portion remains flexible,although it has a higher rigidity with respect to the front portion. Theflexibility and a certain shock-absorption of the rear portion areobtained by making it out of materials such a cork, sawdust, or latex.Therefore, the known sole of this document is not capable oftransmitting forces intended for edge setting, for example, andtherefore does not provide a satisfactory solution to the problemsdescribed hereinabove.

[0028] The same is true with the teachings of the U.S. Pat. Nos.1,428,356 and 3,984,925.

[0029] The French Patent Publication No. 2 743 989 relates to a sole,especially for a boot adapted to sports requiring an unrolling movementof the foot, or to gliding sports. This document describes an outer soleconstituted of a front portion and a rear portion. The rear portioncovers at least the base of the heel and extends up to themetatarsophalangeal bending zone. It is rigid and substantiallynon-flexible. The front portion is flexible and has, at its endcorresponding to the end of the foot, at least one member for couplingto a gliding support such as a cross-country ski. The adjacent front andrear portions overlap one another in the junction zone where they areassembled by cementing or riveting. In the junction or assembly zone,the end involved of the front portion is overlapped by the correspondingend of the rear portion. A stiffener of the upper can be affixedlyattached on the rear portion.

[0030] It appears that such a sole can still be improved with respect totorsional rigidity and the possibility to bend in the area of themetatarsophalangeal joint.

[0031] The German Patent Publication No. 41 20 136 relates to a bootsole, especially a sports boot sole, which is sufficiently flexible inthe area of the forefoot in order not to hinder the rolling/unrollingmovements of the foot, on the one hand, and which is sufficiently rigid,especially in torsion in the journal zone and in the rear portion, onthe other hand. This sports boot sole has a composite material(matrix+woven or nonwoven fibers) in which the continuous fibers areoriented in several directions. This composite material is enclosed in asole body arranged on the edges of the sole, made of thermoplastic orelastomeric material and affixedly attached to the composite material bywelding or chemical bonding, or even by (duplicate) molding. As shown inFIGS. 1 and 2, the sole can have two composite plates 71 a, 71 b locatedin the front portion and in the rear portion, respectively. These twocomposite plates 71 a and 71 b are housed and fixed in a sole bodyforming a frame and including a transverse bridge 72 separating the twoplates 71 a and 71 b.

[0032] As shown in FIG. 6, this sole can include a single element, orcomposite plate 171 extending along the entire length and ensuring atransverse rigidity. In this embodiment, the rear portion has a secondcomposite plate 67 having a longitudinal, diagonal or isotropicrigidity. Also provided is a layer 68 made of rubber, inserted betweenthe composite plates 171 and 67 in the rear portion.

[0033] It must be noted that the peripheral sole body forming a frame inwhich the composite plate or plates are housed and fixed is integral.Therefore, here is a problem related to the industrial manufacture ofthe soles in one piece for several sizes. The drawbacks associated withthis problem, both economical and in terms of workability, have beenpresented hereinabove.

[0034] Moreover, this type of known sole does not offer the possibilityof providing projecting elements on the lower surface of the sole, suchas guiding central grooves or wear resisting adherence pads.

[0035] Furthermore, the sole according to DE 41 20 136 includes arelatively large number of elements, which complicates the industrialmanufacture thereof.

[0036] Finally, the mechanical characteristics (optimizing efficiency,elasticity, resistance) weight, durability, are not optimized.

[0037] Therefore, one has to establish that the prior technicalpropositions are not entirely satisfactory, or are ill-adapted tosolving the overall technical problem consisting of:

[0038] increasing the torsional stiffness:

[0039] so as to improve the steering and the control of the sportsapparatus, especially gliding apparatus (e.g., ski), while optimizingthe bending ability in the metatarsophalangeal zone; and

[0040] so as to enable the foot to perceive the reactions of the terrainand of the apparatus;

[0041] optimizing the flexional flexibility, so as to enable a uniformand easy rolling/unrolling movement of the foot;

[0042] improving the efficiency of the boot by optimizing the springeffect in the metatarsophalangeal zone, without hindering theflexibility and torsional stiffness;

[0043] using materials meeting the mechanical requirements mentionedhereinabove, and capable of maintaining these mechanical qualities overa long period of time;

[0044] further lightening the weight on the boot;

[0045] protecting the foot during bendings by minimizing the compressivestress to which the foot is subject;

[0046] maintaining the production cost within acceptable limits;

[0047] ensuring industrial workability;

[0048] developing a reinforcement that can be easily manufacturedindustrially.

SUMMARY OF THE INVENTION

[0049] One of the objects of the present invention is to provide a bootsole, especially a sports boot sole (e.g., cross-country ski boot),which procures significant advances, in particular with respect theaforementioned technical specifications.

[0050] Another object of the invention is to propose a sole for across-country ski boot which makes it possible to improve theefficiency, steering of the ski, durability, while conserving or gainingflexibility, weight loss, cost, foot protection, and industrialworkability.

[0051] Another object of the present invention is to provide a boot,especially a sports boot, and more specifically a cross-country skiboot, having a reinforcement in the bottom assembly that is capable ofmeeting the aforementioned working specifications as much as possible.

[0052] Another object of the invention is to provide a sole, inparticular an outer sole for a boot, especially a sports boot, which islightweight, requires a small quantity of plastic material, and whichmakes it possible to replace, or even eliminate the conventional insole.

[0053] Another object of the invention is to provide a sole for a boot,especially a sports boot, having a structure such that it is possible tovary the mechanical characteristics in a wide range, without undulycomplicating the manufacturing process.

[0054] Another object of the invention is to propose a manufacturingmethod for the aforementioned sole, as well as a boot provided with sucha sole.

[0055] Another object of the invention is to propose a method ofmanufacturing a boot provided with such a sole.

[0056] To achieve these objects, among other things, credit goes to theinventors for finding a sole that is flexible at the front and rigid atthe rear due to a reinforcement (for example, a composite reinforcementthat is cemented or duplicate molded), this reinforcement beingassembled with two front and rear half-soles affixedly attached to oneanother.

[0057] Therefore, the present invention relates primarily to a sole fora boot, especially a sports boot:

[0058] having a front portion, and a rear portion that is more rigid inlongitudinal bending than the front portion,

[0059] including at least one reinforcement in these two portions,

[0060] wherein:

[0061] the front portion has a front half-sole affixed to thereinforcement,

[0062] the rear portion has a rear half-sole affixed to thereinforcement; and

[0063] the front and rear half-soles are assembled to one another in ajunction zone, preferably, by cementing and/or riveting and/or welding.

[0064] According to the invention, the construction of the sole aroundthe reinforcement (which can also be called a core or an insert), byproviding two distinct half-soles for the front and the rear (preferablyduplicate molded at the front), with an assembly affixed to these twohalf-soles in a junction zone, contributes to achieving the desiredresults in terms of longitudinal flexibility and torsional rigidity inthe front portion, and of longitudinal and torsional stiffness in therear portion. The same is true with respect to:

[0065] the efficiency of the boot (spring effect at the front);

[0066] the steering of a sports apparatus (for example a glidingsupport) possibly coupled to the boot sole;

[0067] durability;

[0068] lightness;

[0069] ease;

[0070] the precision of the rolling/unrolling movement of the foot andof the boot;

[0071] the perception of the sensations coming from the reactions of theterrain and of the apparatus; and

[0072] the protection of the foot during bendings.

[0073] The rigidity and the non-flexibility at the rear enable anefficient transmission of the forces coming from the user's leg, whichare adapted to direct or propel the user's body, especially by enablingan efficient edge setting, or to cooperate with a guiding system of theridge-type in cross-country skiing.

[0074] Preferably, the limit between the front portion, substantiallyflexible in the longitudinal direction and stiff in torsion, and therear portion, rigid in torsion and in the longitudinal direction, islocated substantially at the rear of the so-called metatarsophalangealbending area.

[0075] According to another preferred characteristic of the invention,the two front and rear half-soles overlap one another in the junctionzone, and the length of the junction zone is adjustable depending on thesize.

[0076] The length of this junction zone is adjustable within certainlimits depending on the size. The variation in the overlapping lengthallows for the manufacture of soles of various sizes on the base of theidentical rear and front portions, respectively, which considerablyreduces the production and storage costs through the diminution of thenumber of various parts to be manufactured. This construction alsoprovides a better precision in manufacturing and adjusting the soles tothe boots.

[0077] Clearly, there is a limit to the variation in the overlappinglength L (L1, L2). This limit is due to the length of the reinforcement(for example, composite reinforcement) in relation to the total lengthof the sole, but more so to the length of the half-soles.

[0078] According to a remarkable characteristic of the invention, therear half-sole overlaps the front half-sole in the junction zone.

[0079] Thus, seen from the bottom, the front end zone of the rearhalf-sole is located above and covers the rear end zone of the fronthalf-sole.

[0080] Advantageously, the assembly between the front half-sole and therear half-sole is obtained in this junction/overlapping zone.

[0081] Preferably, the latter is located in and/or behind the so-calledmetatarsophalangeal bending zone.

[0082] Such a construction enables a significant weight loss whileguaranteeing the desired mechanical characteristics due to thereinforcement. Thus, there are less compressive stresses on thereinforcement compared to the known embodiments as described, forexample, in EP 0 931 470, in which the reinforcement is used as aninsole, or as an insole reinforcement.

[0083] The fact that the rear half-sole, in a bottom view, overlaps thefront half-sole in the junction/assembly zone, precisely ensures abetter assembly and makes it possible to prevent incipient separationsof the rear end zone from the front half-sole which bends, since thelatter is sandwiched between the reinforcement and the rigid rearhalf-sole which does not bend.

BRIEF DESCRIPTION OF DRAWINGS

[0084] The invention will be better understood and other characteristicsthereof will become apparent from the description that follows, withreference to the annexed schematic drawings showing, by way ofnon-limiting examples, a plurality of embodiments, and in which:

[0085]FIG. 1 is a bottom view of a sole according the present invention;

[0086]FIG. 2 shows a straight transverse cross-section along the lineII-II of FIG. 1;

[0087]FIG. 3 is a side view of a sole according to a second embodimentof the present invention;

[0088]FIGS. 4a and 4 b are side views of a sole according to thepreferred embodiment of the invention as shown in FIGS. 1 and 2;

[0089]FIG. 5 is a bottom view of an intermediate piece for manufacturingthe sole according to the invention (third embodiment) including thereinforcement on the front area of which the front half-sole isduplicate molded; and

[0090]FIG. 6 is a lateral view of a boot incorporating a sole accordingto the invention (fourth embodiment) as well as a stiffener.

DETAILED DESCRIPTION OF THE INVENTION

[0091]FIGS. 1, 2, 4 a, 4 b correspond to the preferred embodiment of thesole according to the invention.

[0092] In the non-limiting example described here, the sole according tothe invention is an outer sole for a cross-country ski boot, this solebeing generally designated by the reference numeral 1. As shown in thefigures, this sole includes a reinforcement 2, preferably made of acomposite material, which, in this case, is made in the form of aninsert included in two front and rear half-soles designated by thereference numerals 3 and 4, respectively. The front half-sole 3 and therear half-sole 4 are integral with, and can be unitary with, the frontportion and the rear portion, respectively, of the sole 1.

[0093] The front half-sole 3 and the rear half-sole 4 are assembled toone another in a junction zone L, L1, L2, L3 in FIGS. 3, 4a, 4 b, 6,respectively, along a contact plane that can be substantiallyperpendicular (FIG. 3: 2nd embodiment) to the plane of the sole, orwhich forms, with the latter, an angle less than 90°, preferably lessthan or equal to 45° (FIGS. 4a, 4 b, 6: preferred embodiment and 4thembodiment).

[0094] The assembly of the half-soles 3, 4 along this contact plane isobtained by any appropriate means known to a person with ordinary skillin the art, for example, by welding and/or cementing and/or riveting.

[0095] In the preferred embodiment and the fourth embodiment shown inFIGS. 1, 4a, 4 b, and 6, this junction zone corresponds to theintermediate area of the sole 1 in which, above and beneath thereinforcement 2, at least a portion of the front end zone 5 of the rearhalf-sole 4, in a bottom view, overlaps (or covers) the rear end zone 6of the front half-sole 3. This appears clearly in FIGS. 4a, 4 b, and 6in which the junction/overlapping zones are designated by the referencesL1, L2, L3.

[0096] As shown in FIGS. 1, 4a, 4 b, and 6, the rear end zone 6 of thefront half-sole 3 is beveled and covered (in a bottom view) by the frontend zone 5, also beveled, of the rear half-sole 4, beneath thereinforcement 2.

[0097] According to the invention, each front 3 or rear 4 half-soleincludes the constituent material located beneath the reinforcement 2,which material may or may not extend above the reinforcement 2.

[0098] In the preferred embodiment of the sole shown in FIGS. 1 and 2,the front half-sole 3 at least partially encloses the front of thereinforcement 2, such that the constituent material of the fronthalf-sole 3 is present beneath and above the reinforcement 2. On theother hand, the rear half-sole 4 does not, or virtually does not overlapabove the rear of the reinforcement 2.

[0099] It is different with the embodiments shown in FIGS. 3, 4a, 4 b,and 6, according to which the reinforcement 2 is included in the twofront 3 and rear 4 half-soles, such that the constituent material ofthese half-soles is present beneath and above the reinforcement 2.

[0100] With respect to the reinforcement 2, it is preferably constitutedby at least one laminated or non-laminated plate extending from thejunction zone, both on at least half of the front portion and on atleast half of the rear portion.

[0101] Advantageously, the reinforcement 2 has a length correspondingsubstantially to at least 60%, preferably at least 70%, and even morepreferably at least 80%, of the length of the sole.

[0102] It is also preferable that the composite plate 2 forming thereinforcement have a form corresponding substantially to the form of theprojection, on a plane, of a human foot placed on this plane ofprojection. In practice, the total length of the plate 2 correspondssubstantially to 90% of the total length of the sole 1.

[0103] According to one advantageous embodiment of the invention, atleast one of these front 3 or rear 4 portions is designed to cooperatewith a sports apparatus.

[0104] In practice, it is naturally the lower surface of the sole 1, ormore precisely of the front 3 and/or rear 4 half-sole that has a formand means provided to cooperate with a sports apparatus, for example across-country ski. Thus, the half-sole or half-soles 3, 4 themselves canbe constituted by at least one piece 8, 8 a, 9 ₃, 9 ₄, 13 for guidingand/or for connecting to a sports apparatus.

[0105] The result is that, according to an advantageous alternativeembodiment of the invention, the sole 1 has, on its lower surface, inthe front portion and/or rear portion:

[0106] at least one guiding member 8, 9 ₃, 9 ₄, adapted to cooperatewith complementarily shaped guiding means provided on a sportsapparatus, preferably a gliding support (for example a cross-countryski), to which the sole 1 is designed to be coupled; and

[0107] possibly, at least one adherent and wear resisting pad 8 a.

[0108] In addition, according to another interesting alternativeembodiment of the invention, the sole 1, in particular the frontportion, includes at least one member 13 for coupling to a sportsapparatus, preferably a gliding support (for example a cross-countryski).

[0109] According to an embodiment of the invention, at least one of thefront 3 and rear 4 half-soles (preferably the front half-sole) isduplicate molded, co-molded, on the reinforcement 2, this duplicatemolding being preferably selected from the moldable plastic materials,reinforced or non-reinforced, and having appropriate mechanicalqualities for rigidity in the rear portion and flexibility in the frontportion.

[0110] Still preferably, the front half-sole 3 is duplicate molded onthe front of the reinforcement 2 (FIG. 5) and the rear half-sole 4 iscemented on the rear of the reinforcement 2.

[0111] However, it is also possible for the reinforcement to beassembled on the two half-soles by other assembly techniques, such ascementing or riveting.

[0112] The type of constituent matrix material(s) of the front half-sole3 and of the rear half-sole 4 assembled to one another in thejunction/overlapping zone (L, L1, L2, L3) will be discussed in moredetail hereinafter.

[0113] Advantageously, the reinforcement 2 is made of a compositematerial. Thus, it can be constituted of a matrix (for example athermoplastic or thermosetting resin) in which short or long reinforcingfibers are embedded. The reinforcement 2 can also be made in the form ofa composite laminate including one or several textile layers, woven ornonwoven, which are coated and embedded in a preferably thermosettingmatrix, such as polyester or epoxy resins. The textile fibers used are,for example, glass, carbon, or polyaramide fibers.

[0114] According to an improved embodiment, the reinforcement 2 isformed by a plate having a sandwich-type structure including a coreinserted between two single or multi layered laminas. In the case wherethe sandwich structure has a thickness less than or equal to 3 mm, it isreferred to as a “microsandwich,” such a “microsandwich” structure beingpreferably provided in the rear portion.

[0115] The “sandwich” structures are known in the field of compositematerials. Conventionally, at least one of the laminas (preferably both)of the “sandwich” structures is made of composite based on woven ornon-woven fibers included in a matrix.

[0116] The outer laminas are constituted by a material selected from thefollowing group of composites:

[0117] the composites:

[0118] whose matrix is made of thermosetting polymer resin such as epoxyresins, phenolic resins, polyester resins, and their mixtures; and

[0119] whose woven or nonwoven fibrous material includes polyethylenefibers, glass fibers, carbon fibers, polyaramide fibers(poly-paraphenylene-terephthalamide: KEVLAR®), metallic fibers,polyethylene fibers, natural or synthetic textile fibers and theirmixtures; the carbon and glass fibers being more particularly preferred;

[0120] the composites:

[0121] whose polymeric matrix is made of thermoplastic polymer,advantageously made of polyamide, polyurethane, polyolefine, orpolyacrilobutadiene styrene (ABS), and their mixtures; and

[0122] whose woven or nonwoven fibrous material includes glass fibers,carbon fibers, poly-paraphenylene-terephthalamide fibers (KEVLAR®),metallic fibers, natural or synthetic textile fibers and their mixtures;the carbon and glass fibers being more particularly preferred;

[0123] the composite laminates constituted at least partially by one orseveral microsandwich composite sheets each having a thickness less thanor equal to 3 mm and including a core inserted between at least twocomposite laminas.

[0124] By way of examples of fibers that can be used in thesecomposites, one can cite those provided in the table below, whichmentions the type of weaving laps and the mechanical characteristics ofthese networks or fibrous laps. Breaking Stress Modulus greater FibersWeaving greater than than Glass Unidirectional  700 MPa 25000 MPa GlassMultidirectional  350 MPa 12000 MPa Carbon Unidirectional 1500 MPa 70000MPa Carbon Multidirectional  700 MPa 35000 MPa

[0125] Advantageously, the core of the sandwich structure is made ofsynthetic foam, preferably polyurethane, polymethacrylate, polyvinylchloride, of wood or honeycomb, cellular cores. In the case of“microsandwich” structures, the core can be a composite structure havinglower mechanical characteristics and/or cost than those of the laminas.Thus, composite structures having paper or silk embedded in a matrix canbe used.

[0126] In addition to the composites, the reinforcement 2 can be made ofany appropriate material, for example, wood, metal (steel),thermoplastic polymer.

[0127] According to an advantageous alternative embodiment of theinvention, the reinforcement 2 (composite or non-composite) is a platecovered, at least on one of its surfaces, with at least onecompatibility layer adapted to promote compatibility between thereinforcement 2 and the half-sole(s) 3 and 4, preferably duplicatemolded plastic(s), or between the reinforcement 2 and the boot upper, oryet between the (composite or non-composite) reinforcement 2 and therear half-sole. This layer is advantageously constituted by at least onesynthetic film forming polymer, especially selected from the groupincluding polyamides and/or polyolefines and/or polyurethanes.

[0128] According to yet other alternative embodiments, the reinforcement2 can be composed of a plurality of composite plates or layers at leastpartially superimposed or non-superimposed.

[0129] The reinforcement 2 (e.g., composite reinforcement), in this casethe plate, can also be envisioned not to have the shape of the foot andto occupy a markedly smaller surface than that corresponding to thepreferred embodiment (namely 90% of the surface of the sole).

[0130] Furthermore, the reinforcement 2 could be formed of a pluralityof elements that are not in the form of plates.

[0131] In one embodiment, the reinforcement 2 is made of a single-layertype composite formed by an epoxy matrix reinforced by woven carbonfibers.

[0132] The front 3 and rear 4 half-soles will be discussed in moredetail hereinafter.

[0133] As indicated hereinabove, the front and rear half-soles 3, 4 inthe preferred embodiment have, on their lower surface, guiding blocks orribs 8 that define a guiding groove 9 ₃, 9 ₄ along the longitudinal axisβ of the sole 1. A portion 9 ₃ of this guiding groove 9 is arranged inthe front portion, on the front half-sole 3, and another portion 9 ₄ ofthis groove 9 is located in the rear portion, on the rear half-sole 4.

[0134] This guiding groove 9 ₃, 9 ₄ is adapted to cooperate with acomplementarily shaped rib provided on a gliding support, namely across-country ski in this case.

[0135] In this case, these guiding blocks or ribs 8 are constituted bysome types of beams in the longitudinal direction and adapted tocooperate with a correspondingly shaped guiding edge of the binding.

[0136] In addition to the fact that they define the guiding groove 9 ₃,9 ₄, these blocks or ribs 8 have the function of improving the adherenceof the boot sole on the support with which it cooperates, due to theanti-slip pad 8 a with which each is provided. They also have the roleof providing the sole with wear resistance properties, and moreparticularly resistance to abrasion.

[0137] It must also be noted that the longitudinal median axis (M) ofthe front portion forms an angle with the longitudinal median axis (M′)of the rear portion (FIG. 1).

[0138] This FIG. 1 also shows the axis Δ of the metatarsophalangealjoint which corresponds substantially to the bending axis of the frontportion of the sole 1. This axis Δ forms an angle α on the order of 70°with respect to the internal tangent of the sole. In addition, this axisΔ intersects with the longitudinal median axis at a point located atabout 73% of the total length of the sole 1 along the axis β and fromthe heel.

[0139] On their upper surface, the front 3 and rear 4 half-soles have aperipheral edge 10 (duplicate molding) on at least a portion of theperiphery of the sole 1, in this case on the entire periphery. Thisperipheral edge or cementing board 10 is adapted to enable a goodassembly, for example by cementing, of the outer sole 1 with theupper/vamp 11 shown in FIG. 6. This cementing board 10 is designed suchthat it makes it possible to compensate for the imperfections of theupper/vamp 11, namely roughing, fold, stiffener, for example.

[0140] According to another advantageous embodiment of the invention,the sole 1 includes one or several recesses 12 provided at least in itslower surface and showing a portion of the preferably compositereinforcement 2.

[0141] Furthermore, the drawings also show that the front half-sole 3has at least one element 13 for coupling to a gliding support, forexample a cross-country ski. In the present example, it is a transversemetallic cylindrical rod, perpendicular to the axis β and affixedlyfixed by its two ends to the inner flanks of the two guiding blocks orribs 8, in the vicinity of the front end of the sole 1.

[0142] In the embodiment shown in FIG. 5, two coupling elements 13 areprovided.

[0143] The assembly between the front 3 and rear 4 half-soles in thejunction zone L is done with overlapping (FIGS. 1, 4a, 4 b, 6) orwithout overlapping along a plane substantially perpendicular to theplane of the sole (FIG. 3). This assembly is obtained by any known andappropriate means, such as heat bonding, cementing, or riveting, forexample.

[0144] The extreme front limit of the overlapping zone L, L1, L2 isadvantageously constituted by the axis Δ of the metatarsophalangealjoint. For reasons related to progressiveness and comfort, and to ensurea better rolling/unrolling movement of the foot, without rupture, thejunction/overlapping zone L, L1, L2 preferably has a rigidity comprisedbetween that of the rear portion and of the front portion, or even arigidity that diminishes progressively from its zone of junction withthe rear portion, up to its zone of junction with the front portion fora perfect transition with these two extreme rigidities.

[0145] As shown in FIGS. 4a and 4 b, it is possible, in the case of anoverlapping of the front 6 and rear 5 ends of the half-soles 3, 4,respectively, to vary the length L, L1, L2, L3 of thejunction/overlapping zone by modifying the degree of overlapping. InFIG. 4a, the sole has a junction zone having a length L1, and in FIG.4b, the latter has a shorter length L2, such that the total length P1 ofthe sole 1 of FIG. 4a is shorter than the total length P2 (size) of thesole 1 of FIG. 4b. The variation margin is comprised, for example,between 14 and 21 mm. This makes it possible to cover two to three bootsizes, with a single size of the front 3 and rear 4 portions, with areinforcement 2 of a given length, and without significantly modifyingthe manufacturing parameters, which will be developed hereinafter.

[0146] According to an alternative, the reinforcement 2 has, in the rearportion of the sole, one or several upward extensions (at the level ofthe heel, for example) to increase the torsional rigidity.

[0147] According to another alternative, whether or not cumulative withthe above-mentioned alternative, this reinforcement 2 can be associatedwith at least one other reinforcement, preferably at the rear, in orderto increase the rigidity of this portion.

[0148] It can also be envisioned that the reinforcement 2 havelongitudinal corrugations, at least in the metatarsophalangeal bendingzone, to increase the torsional stiffness, without increasing theflexional stiffness.

[0149] The rear half-sole 4 is preferably rigid and substantiallynon-flexible so as to avoid losses of energy by shock-absorption andparasitic deformation, which enables a better transmission of forces. Tothis end, the matrix material selected is advantageously constituted bya plastic material (thermoplastic) with appropriate rigidity, possiblyreinforced by glass or carbon fibers or a metallic material. By way ofexamples of matrix plastic materials for the rear portion, one can cite:polyamides (ZITEL™), polyurethanes, polyacetates, polyoxymethylene,polycarbonates, polyether block amide. In any event, the materials ofthe rear portion and of the composite reinforcement are selected suchthat this rear portion preferably has a modulus of elasticity comprisedbetween 260 MPa and 200 000 MPa.

[0150] The front half-sole 3 is flexible to enable the rolling/unrollingmovements of the foot as naturally as possible. The material(s) used forthe front matrix assembly 3 are therefore selected by taking intoaccount the mechanical qualities specific to the composite reinforcement2 in the front portion. For example, these are plastic materials(thermoplastics) that are suited for the molding techniques. By way ofexamples of such plastic materials, one can cite: polyether block amides(Pebax™), polyamides, polyurethanes, polyacetates, polyoxymethylene,polycarbonates.

[0151] It is clear that each front 3 or rear 4 half-sole can beconstituted of several different materials. In this case, the adherenceand wear resisting pads 8 a are constituted of a material distinct fromthe remainder of the half-sole. For example, it can be elastomers [suchas rubber, styrene-butadiene: “Styrene-Butadiene Rubber” (SBR)],thermoplastic elastomers [such as “thermoplastic-rubber”], orthermoplastics [such as polyurethane (PU), polyethylene butadiene(PEBA), polyamide (PA)].

[0152]FIG. 5 shows an intermediate piece 15 for manufacturing the sole 1according to the invention. This intermediate piece only includes thefront half-sole 3, to which the reinforcement 2 is assembled. In theembodiment shown, this assembly is ensured by duplicate molding thefront half-sole around the front portion of the reinforcement 2. Thereinforcement formed by a composite plate 2 having perforations 7 forenabling the passage of bridges of duplicate molding plastic material(s)forming the front 3 and rear 4 half-sole or half-soles and connectingthe portions of the half-sole or half-soles located above and beneaththe reinforcement 2. The purpose of these perforations 7 is to ensurethat, in obtaining the sole by duplicate molding of the compositereinforcement 2 with plastic matrix material, the latter extends throughthe composite reinforcement. This makes it possible to improve themechanical fixing of the duplicate molded half-sole or half-soles 3, 4on the composite reinforcement 2. In this case, this intermediate pieceonly includes the composite reinforcement 2 with perforations 7, whichcomposite reinforcement is duplicate molded by the front matrix assembly3 which has guiding blocks 8, a groove 9 ₃ and transverse rods 13 forcoupling to the cross-country ski.

[0153] Advantageously, the transverse metallic rods 13, used as couplingmembers, are affixed to the front matrix assembly 3, in the area of thetip of the sole 1, during duplicate molding.

[0154]FIG. 6 shows a boot having an outer sole 1 according to a fourthembodiment of the invention. This sole is affixed to an upper/vamp 11,and has a stiffener 14 in its rear portion.

[0155] This rear portion forms an integral or unitary assembly with thestiffener 14 which covers the heel, the rear portion preferably having adifferent, and even more preferably greater rigidity than that of thestiffener 14.

[0156] This stiffener 14 surrounds the heel of the foot in the manner ofa shell. Preferably, the stiffener 14 extends from the heel zone up tothe metatarsophalangeal natural bending zone L3. The effect of holdingthe heel of the foot, in the manner of a shell, by the integral assemblyformed by the rear portion of the sole 1 and the stiffener 14, ismarkedly improved when the stiffener 14 is substantially rigid and has arigidity similar to that of the sole. Preferably, the rigidity of thestiffener 14 is lower than the rigidity of the rear portion of thenon-flexible sole 1. The choice of rigidity for the stiffener 14, theportion and the rear half-sole 4 of the sole 1, respectively, can bedone optimally by selecting or not selecting a same material for thesethree elements, while keeping the integral assembly. The preferredmaterials for the stiffener 14 are leather or plastic materials possiblyreinforced by inserts made of metallic material or glass or carbonfibers.

[0157] According to an advantageous characteristic of the invention, thefront half-sole 3, the rear half-sole 4, the reinforcement 2, andpossibly the stiffener 14 (FIG. 6), are made of different materials.

[0158] Advantageously, the stiffener 14 could be associated withpossible upward extensions (or lateral extensions) mentioned hereinaboveand not shown in the drawings. These two elements could thus cooperateto provide more torsional rigidity.

[0159] According to another one of its aspects, the present inventionrelates to a method for manufacturing the sole 1 according to theinvention as defined hereinabove.

[0160] Advantageously, this method essentially comprises:

[0161] (1) using a plate 2 adapted to be the reinforcement of the sole 1and having a form corresponding substantially to the form of theprojection, on a plane, of a human foot placed on this plane;

[0162] (2) assembling (by cementing, riveting, or duplicate molding) thereinforcement 2 to a front half-sole 3 to obtain an intermediate piece.

[0163] When the assembly is made by duplicate molding, the assembly stepcomprises:

[0164] (a) placing this reinforcement 2 in a mold whose cavitycorresponds to the form of the front 3 and/or rear 4 (preferably front)half-sole of the sole 1;

[0165] (b) possibly placing in the mold at least one element 13 forcoupling to a sports apparatus, preferably a gliding support;

[0166] (c) duplicate molding the reinforcement 2 by means of identicalor different material(s), preferably different materials at least forthe front half-sole 3 and the rear half-sole 4;

[0167] (d) extracting from the mold the intermediate piece 15 formed bythe reinforcement 2 on which the front half-sole 3 (or the rearhalf-sole 4) is duplicate molded.

[0168] Subsequent to the process, the rear half-sole 4 (or the fronthalf-sole 3) is fixed on the intermediate piece 15, for example, bycementing.

[0169]FIG. 5 shows the intermediate piece 15 as obtained in thepreferred embodiment described hereinabove.

[0170] According to an alternative corresponding to the making of thetwo half-soles 3 and 4 by duplicate molding, in two distinct, successivemolding operations:

[0171] this intermediate piece 15 is placed in a mold of the rearhalf-sole 4 (or front half-sole 3) according to a step a′;

[0172] the rear half-sole 4 (or front half-sole 3) is duplicate moldedaccording to a step b′;

[0173] the sole including the duplicate molded reinforcement 2 isextracted from the mold.

[0174] According to an alternative of the method according to theinvention leading to the sole of the boot of FIG. 6, a stiffener 14 isaffixedly fixed to the rear matrix assembly of the sole 1, such thatthey form an integral or unitary assembly.

[0175] Due to its design and particularly to its manufacture, at leastpartially, by duplicate molding:

[0176] the sole according to the invention has thin layers of plasticmaterial, such that the plastic matrix is less sensitive to aging withrespect to the mechanical properties;

[0177] it can be envisioned to use a single mold for the sole to obtainvariable mechanical characteristics by merely duplicate moldingreinforcements of various forms and thicknesses.

[0178] According to another one of its aspects, the invention relates toa quite particular and advantageous method of manufacturing a boot,especially a sports boot. This method comprises:

[0179] using the intermediate piece 15;

[0180] assembling the latter, preferably by cementing, to the upperportion of the boot (upper/vamp); and

[0181] fixing the rear half-sole 4 (or the front half-sole 3),preferably by cementing, on the intermediate piece 15 assembled to theupper portion of the boot (upper/vamp).

[0182] Still regarding the boot manufacture according to the invention,it must be noted that the sole having one or two half-soles can be usedin a “strobel” type assembly method (upper peripherally sewn to a“strobel” sole), which makes it possible to avoid the need of aconventional insole which is more rigid and heavier, resulting in asignificant weight loss.

[0183] In all of these sole and/or boot manufacturing methods, all typesof conventional assemblies can be used: cementing, welding, duplicatemolding, screwing, riveting.

[0184] According to another one of its objects, the present inventionrelates to a boot, especially a sports boot, having a sole 1 as definedhereinabove, or a sole 1 obtained by the aforementioned method.

[0185] The invention also relates to a boot such as defined in theprevious paragraph, and which pertains to the group including:

[0186] ski boot, in particular cross-country or telemark ski boot;

[0187] cycling shoe;

[0188] roller skate;

[0189] ice skate;

[0190] or any other sport requiring the coupling of a boot to a sportsapparatus, such as rowing, water skiing, wakeboarding, surfing,snowboarding, ski surfing, climbing crampons.

[0191] Finally, the invention relates to the use of the sole 1 asdescribed hereinabove, as such or as a product obtained by the methodaccording to the invention, for the manufacture of a boot as describedhereinabove.

What is claimed is:
 1. A sole for a boot, especially a sports boot, saidsole comprising: a front portion and a rear portion more rigid inlongitudinal bending than the front portion, at least one reinforcementin said two portions, wherein: the front portion comprises a fronthalf-sole affixed to the reinforcement; the rear portion comprises arear half-sole affixed to the reinforcement; and the front and rearhalf-soles are assembled to one another in a junction zone, preferably,by cementing and/or riveting and/or welding.
 2. A sole according toclaim 1, wherein the limit between the flexible front portion and therigid rear portion is located substantially at the rear of the so-calledmetatarsophalangeal bending zone.
 3. A sole according to claim 1,wherein the two front and rear half-soles overlap one another in thejunction zone and wherein the length of the junction zone is adjustabledepending on the size.
 4. A sole according to claim 3, wherein the rearhalf-sole (seen from the bottom) overlaps the front half-sole in thejunction zone.
 5. A sole according to claim 1, wherein thejunction/overlapping zone is located in and/or behind the so-calledmetatarsophalangeal bending zone.
 6. A sole according to claim 1,wherein it includes a reinforcement constituted by at least onelaminated or non-laminated plate extending from the junction zone, bothon at least half of the front portion and on at least half of the rearportion.
 7. A sole according to claim 1, wherein the reinforcement has alength corresponding substantially to at least 60%, preferably at least70% and even more preferably at least 80%, of the length of the sole. 8.A sole according to claim 1, wherein at least one of its front or rearportions is designed to cooperate with a sports apparatus.
 9. A soleaccording to claim 1, wherein at least one of the front or rearhalf-soles is constituted by at least one piece for guiding and forconnecting to a sports apparatus.
 10. A sole according to claim 9,wherein it has, on its lower surface, in the front portion and/or rearportion: at least one guiding member, adapted to cooperate withcomplementarily shaped guiding means provided on a sports apparatus,preferably a gliding support, to which the sole is designed to becoupled; and possibly, at least one adherent and wear resisting pad. 11.A sole according to claim 1, wherein the reinforcement is assembled tothe front and rear portions of the sole by cementing.
 12. A soleaccording to claim 1, wherein at least one of the front or rear(preferably front) half-soles is duplicate molded on the reinforcement,this duplicate molding being preferably selected from the moldableplastic materials, reinforced or non-reinforced, and having appropriatemechanical qualities for rigidity in the rear portion and flexibility inthe front portion.
 13. A sole according to claim 12, wherein the fronthalf-sole is duplicate molded on the reinforcement, and wherein the rearhalf-sole is cemented on the reinforcement.
 14. A sole according toclaim 1, wherein the reinforcement is made of a composite material. 15.A sole according to claim 1, wherein the reinforcement has a sandwichstructure.
 16. A sole, wherein the reinforcement has a sandwichstructure having a thickness less than or equal to 3 mm.
 17. A soleaccording to claim 1, wherein the reinforcement is a plate covered, atleast on one of its surfaces, with at least one compatibility layer,advantageously constituted by at least one synthetic film formingpolymer, especially selected from the group including polyamides and/orpolyolefines and/or polyurethanes.
 18. A sole according to claim 12,wherein the reinforcement is a plate comprising perforations adapted toenable the passage of bridges of molding material(s) connecting theportions of the half-sole located above and beneath the reinforcement.19. A sole according to claim 1, wherein the front portion comprises atleast one element for coupling to a gliding support.
 20. A soleaccording to claim 1, wherein, in the rear portion, the reinforcementhas one or several upward extensions, and/or is associated with at leastone other reinforcement.
 21. A sole according to claim 1, wherein therear portion forms an integral assembly with a stiffener covering theheel, the rear portion preferably having a different, and even morepreferably greater rigidity than that of the stiffener.
 22. A soleaccording to claim 1, wherein the front half-sole, the rear half-sole,the reinforcement, and possible the stiffener, are made of differentmaterials.
 23. A sole according to claim 1, wherein it is an outer sole.24. A sole according to claim 1, wherein it includes one or severalrecesses provided at least in its lower surface and showing a portion ofthe reinforcement.
 25. A method of manufacturing a sole according toclaim 1, said method comprises: using a plate adapted to be thereinforcement of the sole and having a form corresponding substantiallyto the form of the projection, on a plane, of a human foot placed onthis plane; assembling (by cementing, riveting, or duplicate molding)the reinforcement to a front half-sole to obtain an intermediate piece.26. A method of manufacturing the sole according to claim 25, whereinthe assembly, obtained by duplicate molding, the assembly stepcomprises: placing the reinforcement in a mold whose cavity correspondsto the form of the front and/or rear (preferably front) half-sole of thesole; possibly placing in the mold at least one element for coupling toa sports apparatus, preferably a gliding support; duplicate molding thereinforcement by means of identical or different material(s), preferablydifferent at least for the front half-sole and the rear half-sole;extracting from the mold the intermediate piece formed by thereinforcement on which the front half-sole (or the rear half-sole) isduplicate molded.
 27. A method according to claim 26, wherein: a mold ofthe front (or rear) half-sole is used in the duplicate molding step; theduplicate molding of the front (or rear) half-sole is then undertakenaccording to the step 3; one then retrieves an intermediate piece formedby the reinforcement on which the front half-sole (or the rearhalf-sole) is duplicate molded.
 28. A method of manufacturing the soleaccording to claim 25, wherein, subsequent to the process, the rearhalf-sole (or the front half-sole) is fixed on the intermediate piece,for example by cementing.
 29. A method according to claim 25, wherein:the intermediate piece is placed in a mold of the rear (or front)half-sole; the rear (or front) half-sole is duplicate molded; the solecomprising the duplicate molded reinforcement is extracted from themold.
 30. A method of manufacturing a boot, especially a sports boot,said method comprising: manufacturing an intermediate piece comprising asole front portion on which a reinforcement is assembled; assembling theintermediate piece, preferably by cementing, to an upper portion of theboot (vamp/upper); and fixing a rear half-sole (or a front half-sole),preferably by cementing, on the intermediate piece assembled to theupper portion of the boot (vamp/upper).
 31. A boot, especially sportsboot, wherein it comprises a sole according to claim
 1. 32. A boot,especially sports boot, wherein it comprises a sole manufactured by themethod according to claim
 25. 33. A boot, especially sports boot,wherein it comprises a boot made according to manufacturing methodaccording to claim
 30. 34. A boot according to claim 31, adapted to befixed on a sports apparatus, preferably pertaining to the groupincluding: ski boot, in particular cross-country or telemark ski boot;cycling shoe; roller skate; ice skate; rowing; water ski; surf;snowboard; ski surf; wakeboard; climbing crampons.
 35. A use of the soleaccording to claim
 1. 36. A use of the sole according to the method ofclaim
 25. 37. A use of the sole according to the intermediate piece asdefined in claim
 25. 38. A use of the sole according to themanufacturing of a boot according to claim 30.